# Drag acting on an intruder in a three-dimensional granular environment

## TL;DR

This study numerically investigates the drag force on an intruder in a three-dimensional frictionless granular medium, revealing how size, speed, and volume fraction influence the drag behavior.

## Contribution

It provides new insights into the dependence of drag on intruder size, speed, and volume fraction in 3D granular environments, especially near the jamming point.

## Key findings

- No yield force without gravity.
- Drag proportional to cross section.
- Crossover from quadratic to linear speed dependence.

## Abstract

The drag acting on an intruder in a three-dimensional frictionless dry granular environment is numerically studied. It is found the followings: (i) There is no yield force for the motion of the intruder without the gravity. (ii) The drag is proportional to the cross section of the moving intruder. (iii) If the intruder is larger than surrounding grains, the drag is proportional to the moving speed $V$ of the intruder for dense systems, but it exhibits a crossover from quadratic to linear dependences of the moving speed when the volume fraction of the surrounding grains is much lower than the jamming point. (iv) There is a plateau regime where the drag is almost independent of $V$ if the size of the intruder is identical to those of the environmental grains and the volume fraction is near the jamming point.